WIMBLEDON, England – Petra Kvitova and Lucie Safarova stood just inside the door of Wimbledon’s Centre Court clubhouse, waiting to be called to their semifinal match. The two have been friends, training partners and Fed Cup teammates in the Czech Republic for years.

They wore matching Nike headbands and dresses. They chatted and smiled. Martina Navratilova, the Czech-born champion, said they looked like doubles partners.

The doors opened to a warm reception and a sunny day. But niceties evaporated quickly.

The sixth-seeded Kvitova, the 2011 Wimbledon champion, broke the 23rd-seeded Safarova’s first serve, survived a first-set tiebreaker and moved into Saturday’s final with a 7-6 (8-6), 6-1 victory.

“It was a tough match, mentally as well, because Lucie is a good friend of mine,” the 24-year-old Kvitova said.

There will be no such camaraderie Saturday, when Kvitova plays 13th-seeded Eugenie Bouchard, a 20-year-old Canadian seemingly on a rocket ride toward an elite level of women’s tennis.

Bouchard, like Kvitova, tiptoed through a first-set tiebreaker to seize enough momentum to carry her to the final, beating third-seeded Simona Halep of Romania 7-6 (7-5), 6-2.

Bouchard barely cracked a smile. That was partly because she was exasperated at needing six match points and an extra game to finish. It was mostly because Bouchard seems hard-wired to stay focused.

“I feel like my job is not done here, so there’s no need for a huge celebration because, you know, I’m still working,” she said.

The quartet of semifinalists demonstrated, again, that any predictability at the top of women’s tennis has been gone for years. Increasingly, each Grand Slam event arrives with no real expectation of who will be left to challenge for the title, which is how this year’s Wimbledon semifinals felt — almost like pairings drawn from a hat.

In each year since 2011, three different women have won the first three Grand Slam events: the Australian Open, the French Open and Wimbledon.

Kvitova, comparatively, is dependable in late June and early July. She won the final three years ago, beating Maria Sharapova in straight sets. Her size and power make her a formidable opponent for anyone on the quick grass, and she has made perennial trips to the quarterfinals or beyond since 2010.

She has won 25 of her past 28 matches at Wimbledon.

Kvitova will find a no-nonsense opponent in Bouchard, whose match with Halep felt like the day’s bigger attraction. Their upward trajectories collided on the sport’s most celebrated court.

Bouchard is the only woman to reach the semifinals in the year’s first three majors.